嘉峪关市中心城区扩张过程及其景观特征变化

以中国干旱区嘉峪关市1986、1996、2006和2010年Landsat TM/ETM＋影像为数据源,采用道路扩展和城市建设用地扩张强度反映城区建设扩张过程,同时分析了城市景观类型的斑块特征和结构特征,研究结果表明：1）嘉峪关市中心城区主干道路扩展显著,城市面积增加明显。1986—2010年间嘉峪关市道路长度增加了100.20 km,城市面积从1986年的2 220.03hm^2增加到2010年的5 048.22hm^2,年均扩张强度指数达5.10%。2）城市景观格局变化显著,建设用地、城市绿地和水体分别增加了2 003.74hm^2、655.30hm^2和169.15hm^2,未利用地则减少2 828.19hm^2。建设用地和城市绿地破碎度增加,未利用地破碎度减少。3）城市景观斑块类型更趋均衡化,整体景观和异质性多样性增加。4）城市扩张是嘉峪关城市绿地和水体明显增加的重要原因,人类活动对城市生态环境的影响逐渐增强。

Urban Expansion and Landscape Characteristics of Land Cover of Jiayuguan City during 1986-2010

On the basis of the Landsat TM/ETM＋ images of Jiayuguan City in arid area of China in 1986,1996,2006 and 2010,the change of urbanization and land cover were detected by the main road network and urban expansion index,and the spatial and temporal changes of landscape pattern were analyzed.The result indicated： 1） While the main road expanded obviously,the area of city increased rapidly.The length of main road of Jiayuguan City increased 100.20 km,urban area grew at an average annual rate of 5.10% and increased from 2 220.03 hm^2 in 1986 to 5 048.22 hm^2 in 2010.2）The temporal landscape patterns of Jiayuguan City changed differently from 1986 to 2010.The areas of construction land,urban greenland and water area increased 2 003.74 hm^2,655.30 hm^2 and 169.15 hm^2,however,the unused land decreased 2 828.19 hm^2 during the past 25 years.The fragmentation of urban greenland and construction land increased,but the fragmentation of unused land decreased.3） The patch types and distribution were becoming more balance,the total diversity and heterogeneity were increased.4） The whole landscape of Jiayuguan City was strongly affected by human activities.Urban green land and water area played an important role in maintaining and improving urban environment,and urbanization caused the increase of urban green land.